The present invention relates to a carbon dioxide gas (CO2) incubator or a multigas incubator as an incubator to incubate cultures (samples) such as cells or microbes.
The incubator maintains a temperature and a CO2 concentration constant therein (in incubation room) and makes the inside sterile to incubate cultures (samples) such as cells or microbes which are incubation targets. Thus, the inside of the incubator must be subjected to periodic sterilization treatment. To incubate the samples, a heater and its controller are disposed to adjust a temperature in the incubation room (storeroom).
Additionally, as disclosed in Japanese Patent Application Laid-Open Nos. 8-322552 and 2000-166536, there have been incubators each of which comprises an air layer (air jacket) around an incubation room to promote heat insulation thereof from the outside of the incubator and heat transfer by natural convection.
On the other hand, the important and precious cells or microbes which are incubation targets are placed and incubated in the incubator. However, since there are a plurality of joints or an infinite number of very small holes in a metal inner box which defines the air jacket and the incubation room, the air jacket and the incubation room are not cut off from each other in terms of an air flow. Consequently, it is impossible to block an entry of contaminated air into the incubation room from the outside due to an opening/closing operation of an inner door, air flow noncutting-off or the like. Hence, there is a fear that even when sterilization treatment is executed for each incubation, the entered contaminated air may cause breeding of saprophytic bacterias in the samples (cultures) to be incubated or impossibility of incubating normal samples. Furthermore, since the incubator may inject a CO2 gas into the incubation room, certain gas leakage inevitably occurs because of a pressure fluctuation which accompanies the injection.